Display substrate, method of manufacturing the same and electrowetting display panel having the display substrate

ABSTRACT

A display substrate includes a base substrate, a reflection-polarization member, a first electrode, an insulation layer and a pixel wall. The reflection-polarization member is disposed on the base substrate to reflect and polarize incident light. The first electrode is disposed in a unit pixel area of the reflection-polarization member. The insulation layer is disposed on the first electrode. The pixel wall is disposed on the insulation layer and defines the unit pixel area. Therefore, the entire area of a unit pixel may be used as a reflective area or a transmissive area, and thus an aperture ratio may be improved in a reflection mode or a transmission mode.

PRIORITY STATEMENT

This application claims priority under 35 U.S.C. §119 to Korean PatentApplication No. 2008-132748, filed on Dec. 24, 2008 in the KoreanIntellectual Property Office (KIPO), the contents of which are hereinincorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Technical Field

Example embodiments of the present invention relate to a displaysubstrate, and, more particularly, to a display substrate used in anelectrowetting display device, a method of manufacturing the displaysubstrate, and an electrowetting display panel having the displaysubstrate.

2. Discussion of the Related Art

An electrowetting technique refers to coating a hydrophobic insulator onan electrode and varying the contact angle of a conductive liquid (e.g.,water) and an interface shape of the conductive liquid and anon-conductive liquid (e.g., oil) by controlling surface characteristicsof the hydrophobic insulator. Surface characteristics of the hydrophobicinsulator are controlled by applying a voltage to the electrode and theconductive liquid, when the conductive liquid and the non-conductiveliquid contact each other on the coated hydrophobic insulator. When avoltage is applied to a counter electrode that contacts water and apixel electrode disposed under the hydrophobic insulator, the nature ofthe interface is changed to hydrophilic. The water is moved to contactthe changed hydrophobic insulator, and thus the water pushes the oilbecause the contact angle of the water is decreased. As a result,contrast is displayed through the reflection of light.

A display device employing the electrowetting technology does not use apolarization plate, so that the display device employing theelectrowetting technology has superior transmittance and reflectance,low manufacturing costs and power consumption and fast response time.Accordingly, there is a need for a display using the electrowettingtechnology.

SUMMARY OF THE INVENTION

Example embodiments of the present invention provide a display substratecapable of using the entire area of a unit pixel area as a reflectivearea or a transmissive area, a method of manufacturing the displaysubstrate, and a display device having the display substrate.

According to an embodiment of the present invention, a display substrateincludes a base substrate, a reflection-polarization member, a firstelectrode, an insulation layer and a pixel wall. Thereflection-polarization member is disposed on the base substrate toreflect and polarize incident light. The first electrode is disposed ina unit pixel area of the reflection-polarization member. The insulationlayer is disposed on the first electrode. The pixel wall is disposed onthe insulation layer and defines the unit pixel area.

According to an embodiment, the reflection-polarization member mayinclude a plurality of wire grids spaced apart from each other at auniform distance.

According to an embodiment, the display substrate may further include aswitching element connected to a gate line and a data line crossing thegate line to drive the unit pixel area and the first wall may overlapwith the gate line and the data line.

According to an embodiment, the reflection-polarization member mayinclude a half mirror.

According to an embodiment, the display substrate may further include atleast one second pixel wall dividing the unit pixel area into at leastone sub-pixel area.

According to an embodiment, the display substrate may further include alight-blocking bar overlapping with the second pixel wall.

According to an embodiment, the first electrode may include at least onepattern. The pattern may be formed in the sub-pixel area.

According to an embodiment of the present invention, there is provided amethod of manufacturing a display substrate. In the method, a switchingelement and a reflection-polarization member reflecting and polarizingincident light are formed on a base substrate. A first electrode isformed on the base substrate on which the switching element and thereflection-polarization member are formed. An insulation layer is formedon the base substrate on which the first electrode is formed. A firstpixel wall defining a unit pixel area is formed on the base substrate onwhich the insulation layer is formed.

According to an embodiment, forming the switching element and thereflection-polarization member includes forming a gate pattern bypatterning a gate metal layer on the base substrate, wherein the gatepattern includes a gate electrode connected with a gate line and aplurality of wire grids, forming the gate insulation layer on the basesubstrate on which the gate pattern is formed, forming a semiconductorpattern on the base substrate on which the gate insulation layer isformed so that the semiconductor pattern overlaps the gate electrode atleast in part, and forming a source pattern by patterning a source metallayer on the base substrate on which the semiconductor pattern isformed, wherein the source pattern includes a data line intersecting thegate line, a source electrode of the switching element connected to thedata line and a drain electrode spaced apart from the source electrode.

According to an embodiment, forming the switching element and thereflection-polarization member includes forming a half mirror bydepositing a metal layer on the base substrate, forming a passivationfilm on the base substrate on which the half mirror is formed, forming agate pattern by patterning a gate metal layer on the base substrate onwhich the passivation film is formed, wherein the gate pattern comprisesa gate line and a gate electrode connected to the gate line, forming thegate insulation layer on the base substrate on which the gate pattern isformed, forming a semiconductor pattern on the base substrate on whichthe gate insulation layer is formed so that the semiconductorcorresponds to the gate electrode and forming a source pattern bypatterning a source metal layer on the base substrate on which thesemiconductor pattern is formed, wherein the source pattern includes adata line intersecting the gate line, a source electrode of theswitching element connected to the data line and a drain electrodespaced apart from the source electrode.

According to an embodiment of the present invention, an electrowettingdisplay panel includes a display substrate, an opposite substrate and aliquid layer. The display substrate includes a first base substrate, areflection-polarization member disposed on the first base substrate toreflect and polarize incident light, a first electrode disposed on thereflection-polarization member, and a first pixel wall disposed on thefirst electrode, wherein the first pixel wall defines a unit pixel area.The opposite substrate faces the display substrate. The oppositesubstrate includes a color filter and a second electrode formed on thecolor filter. The liquid layer is interposed between the displaysubstrate and the opposite substrate. The liquid layer includes a firstliquid having a material absorbing light and a second liquid having aspecific gravity different from the specific gravity of the firstliquid.

According to the embodiments of the present invention, areflection-polarization member that reflects and polarizes incidentlight is employed therein, so that the entire area of a unit pixel areamay be used as a reflective area or a transmissive area.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will become moreapparent by describing in detail example embodiments thereof withreference to the accompanying drawings, in which:

FIG. 1 is a plan view illustrating an electrowetting display panelaccording to an exemplary embodiment of the present invention;

FIG. 2 is a cross-sectional view taken along a line I-I′ in FIG. 1;

FIG. 3 is a perspective view illustrating a reflection-polarizationmember of FIG. 2;

FIGS. 4A through 4C are cross-sectional views illustrating a method ofmanufacturing the display substrate of FIG. 2;

FIG. 5 is a cross-sectional view illustrating a display state of theelectrowetting display panel of FIG. 2 when an electric field is notapplied to the electrowetting display panel;

FIG. 6 is a cross-sectional view illustrating a display state of theelectrowetting display panel of FIG. 2 when the electric field isapplied to the electrowetting display panel;

FIG. 7 is a cross-sectional view illustrating a display device includingthe electrowetting display panel of FIG. 2;

FIG. 8 is a plan view illustrating an electrowetting display panelaccording to an exemplary embodiment of the present invention;

FIG. 9 is a cross-sectional view taken along a line II-II′ in FIG. 8;

FIG. 10 is a cross-sectional view illustrating a display deviceincluding the electrowetting display panel of FIG. 9;

FIG. 11 is a cross-sectional view illustrating an electrowetting displaypanel according to an exemplary embodiment of the present invention;

FIGS. 12A through 12C are cross-sectional views illustrating a method ofmanufacturing the display substrate of FIG. 11; and

FIG. 13 is a cross-sectional view illustrating a display deviceincluding the electrowetting display panel of FIG. 11.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The embodiments of the present invention are described more fullyhereinafter with reference to the accompanying drawings, in whichexample embodiments of the present invention are shown. The presentinvention may, however, be embodied in many different forms and shouldnot be construed as limited to the example embodiments set forth herein.In the drawings, the sizes and relative sizes of layers and regions maybe exaggerated for clarity.

It will be understood that when an element or layer is referred to asbeing “on,” “connected to” or “coupled to” another element or layer, itcan be directly on, connected or coupled to the other element or layeror intervening elements or layers may be present. Like numerals mayrefer to like elements throughout.

FIG. 1 is a plan view illustrating an electrowetting display panelaccording to an exemplary embodiment of the present invention. FIG. 2 isa cross-sectional view taken along a line I-I′ in FIG. 1. FIG. 3 is aperspective view illustrating a reflection-polarization member of FIG.2.

Referring to FIGS. 1 to 3, the electrowetting display panel 400according to an embodiment of the present invention includes a displaysubstrate 100, an opposite substrate 200 and a liquid layer 300.

The display substrate 100 includes a first base substrate 101, a gateline GL, a plurality of wire grids 110, a gate insulation layer 120, adata line DL, a switching element TFT, an organic layer 140, a firstelectrode 150, a hydrophobic insulation layer 160 and a firsthydrophilic pixel wall 170.

The first base substrate 101 may be formed with a transparent insulationmaterial. For example, the first base substrate 101 may include a glasssubstrate, a soda-lime substrate, a plastic substrate, etc.

The gate lines GL are formed on the first base substrate 101. The gatelines GL are extended in a first direction D1. The plurality of gatelines GL may be arranged in a second direction D2 substantiallyperpendicular to the first direction D1.

The data lines DL are extended in the second direction D2. The pluralityof data lines DL may be arranged in the first direction D1.

The wire grids 110 are formed on the first base substrate 101. The wiregrids 110 have a predetermined wire width ‘W’ and a thickness ‘T’. Thewire grids 110 are extended along the first direction D1 and disposedalong the second direction D2. The wire grids 110 may be spaced apartfrom each other at a substantially uniform distance. The wire grids 110may be formed in a stripe shape. The wire grids 110 may include amaterial of which reflectance is high and a light-absorption ratio islow. For example, the wire grids 110 may include a metal such asaluminum (Al), silver (Ag), copper (Cu), molybdenum (Mo), etc.

The wire grids 110 reflect and polarize incident light into a firstsurface of the first base substrate 101 or incident light into a secondsurface of the first base substrate 101 opposite to the first surface.Light having an electric field vector substantially parallel to anextending direction (i.e., a first direction D1) of the wire grids 110is defined as an s-polarized light, and light having an electric fieldvector substantially perpendicular to the extending direction D1 of thewire grids 110 is defined as a p-polarized light. The wire grids 110reflect the s-polarized light and transmit the p-polarized light.Therefore, most of light transmitted through the wire grids 110 is thep-polarized light.

A polarization function of the wire grids 110 depends on the wire width‘W’, the thickness ‘T’ and a pitch ‘P’ of the respective wire grids 110.The pitch ‘P’ is defined as an interval between the wire grids 110. Thepitch ‘P’ may be shorter than the wavelength of the incident light for agood polarization function of the wire grids 110. For example, when theincident light is visible light, the pitch ‘P’ is designed to be notgreater than about 400 nm because the wavelength of the visible light isabout 400 run through about 700 nm. Therefore, according to anembodiment of the present invention, the pitch ‘P’ is be designed to benot greater than about 100 nm, resulting in a good polarization functionof the wire grids 110. The wire width ‘W’ of respective wire grids 110is designed to be not greater than about 100 nm. The thickness ‘T’ ofrespective wire grids 110 is designed to be about 150 nm to about 200nm.

The gate insulation layer 120 is disposed on a gate electrode GE of theswitching element TFT and the wire grids 110.

The switching element TFT includes the gate electrode GE, a sourceelectrode SE, a semiconductor pattern 130 and a drain electrode DE. Thegate electrode is electrically connected with the gate line GL and thesource electrode SE is electrically connected with the data line DL. Thesemiconductor pattern 130 on the gate insulation layer 120 overlaps thegate electrode GE, at least in part. The semiconductor pattern 130includes a semiconductor layer 130 a and an ohmic contact layer 130 b.The drain electrode DE is disposed to be spaced apart from the sourceelectrode at a predetermined distance.

The organic layer 140 disposed on the first base substrate 101 on whichthe switching element TFT is formed. The organic layer 140 may be formedwith a photosensitive organic material. The organic layer 140 mayflatten the display substrate 100 and the organic layer may be omittedin accordance with design constraints. The organic layer 140 includes acontact hole CNT exposing an end portion of the drain electrode DE.

The first electrode 150 is disposed on the first base substrate 101 onwhich the organic layer 140 is formed, and the first electrode 150 maybe formed with a transparent conductive material. For example, the firstelectrode 150 may be formed with indium tin oxide (ITO), indium zincoxide (IZO), etc. The first electrode 150 may be electrically connectedwith the switching element TFT by contacting the drain electrode DEthrough the contact hole CNT. The first electrode 150 may cover the unitpixel area P divided by the first hydrophilic pixel wall 170. The firstelectrode 150 may include a plurality of hole patterns 155. Each of thehole patterns 155 may have a circular shape.

Referring, for example, to FIG. 1, a case in which three hole patterns155 are formed in the first electrode 150 is described and shown as anexample; however, different numbers of hole patterns may be formed inthe first electrode 150. For example, one hole pattern 155 may be formedin the first electrode 150.

The hydrophobic insulation layer 160 is disposed on the base substrate101 on which the first electrode 150 is formed.

The first hydrophilic pixel wall 170 is disposed on the base substrate101 on which the hydrophobic insulation layer 160 is formed. The firsthydrophilic pixel wall 170 defines the unit pixel area. The firsthydrophilic pixel wall 170 may be formed with a transparent material.The first hydrophilic pixel wall 170 is formed on an opaque metal line.For example, the first hydrophilic pixel wall 170 may be formed on thegate line GL and the data line DL.

The opposite substrate 200 may include a second base substrate 201, acolor filter 210 and a second electrode 220.

Like the first base substrate 101, the second base substrate 201 may beformed with a transparent insulation material.

The color filter 210 is disposed on the second base substrate 201. Thecolor filter 210 may include a red color filter, a green color filterand a blue color filter.

The second electrode 220 is disposed on the second base substrate 201 onwhich the color filter 210 is formed and the second electrode 220 may beformed with a transparent conductive material. The second electrode 220may cover a front surface of the second base substrate 201. For example,the second electrode 220 may cover the unit pixel area P of the secondbase substrate. The second electrode may be formed with ITO, IZO, etc.

The liquid layer 300 is interposed between the display substrate 100 andthe opposite substrate 200. The liquid layer 300 may include a firstliquid 310 and a second liquid 320. The specific gravity of the firstliquid 310 is different from the specific gravity of the second liquid320, and thus the first liquid 310 and the second liquid 320 form aboundary. The first liquid 310 serves as a light shutter blocking andtransmitting light. The first liquid 310 may be a black dye or oilincluding a material absorbing light. The second liquid 320 hasconductivity and polarity, and may be, for example, water.

FIGS. 4A through 4C are cross-sectional views illustrating a method ofmanufacturing the display substrate of FIG. 2.

Referring to FIGS. 2 and 4A, a gate metal layer is formed on the firstbase substrate 101. The gate line GL, the gate electrode GE and the wiregrids 110 are formed by patterning the gate metal layer. The gateelectrode GE and the wire grids are separated from each other. The wiregrids 110 may be formed by using a laser interference lithography methodor a nanoimprint lithography method.

According to the laser interference lithography method, a photoresist iscoated after a metal layer is deposited on a substrate. The photoresistis exposed by using a mask on which a pattern is formed and aphotoresist pattern is formed by developing the exposed photoresist. Themetal layer is patterned through an etching process and the photoresistis eliminated to form the wire grids 110.

According to the nanoimprint lithography method, a coating layer isformed on a substrate and the coating layer is pressed by a mold onwhich a pattern is formed. The coating layer is hardened by using heator ultraviolet (UV) rays and the mold is separated from the coatinglayer to form the wire grids 110 on the coating layer. A metal layer isdeposited on the wire grids 110.

Referring to FIGS. 2 and 4B, the gate insulation layer 120 is formed onthe first base substrate 101 on which the gate metal pattern is formed.The gate insulation layer 120 may be formed with silicon nitridematerial or silicon oxide material, etc.

The semiconductor layer 130 a and the ohmic contact layer 130 b aresequentially deposited on the first base substrate 101 on which the gateinsulation layer 120 is formed, and the semiconductor pattern 130 isformed by patterning the semiconductor layer 130 a and the ohmic contactlayer 130 b. The semiconductor layer 130 a may be formed with amorphoussilicon and the ohmic contact layer 130 b may be formed with amorphoussilicon highly doped with n-type impurities.

A source metal layer is formed on the first base substrate 101 on whichthe semiconductor pattern 130 is formed. A source metal patternincluding the data line DL, the source electrode SE and the drainelectrode DE is formed through a photoetching process of the sourcemetal layer.

Referring to FIGS. 2 and 4C, the organic layer 140 is formed on thefirst base substrate 101 on which the source metal pattern is formed,and the contact hole CNT is formed exposing the end portion of the drainelectrode DE by exposing and developing the organic layer 140.

A transparent conductive layer is formed on the first base substrate 101on which the contact hole CNT is formed. The first electrode 150 isformed by patterning the transparent conductive layer.

FIG. 5 is a cross-sectional view illustrating a display state of theelectrowetting display panel of FIG. 2 when an electric field is notapplied to the electrowetting display panel.

Referring to FIG. 5, when a voltage is not applied to the firstelectrode 150 and the second electrode 220, the first liquid 310 iswidely spread on the hydrophobic insulation layer 160. Therefore,external light that is incident light from the exterior or internallight that is incident light from an internal light source device (notshown) is absorbed by the first liquid 310. Therefore, the display stateof the electrowetting display panel 400 is a dark state.

FIG. 6 is a cross-sectional view illustrating a display state of theelectrowetting display panel of FIG. 2 when the electric field isapplied to the electrowetting display panel.

Referring to FIG. 6, when a voltage is applied to the first electrode150 and the second electrode 220, the first liquid 310 in the liquidlayer 300 is gathered adjacent to the hole pattern 155 formed on thefirst electrode 150. Therefore, incident light substantially parallel tothe wire grids 110, among incident light from the exterior, is reflectedby the wire grids 110 and transmitted through the liquid layer 300.Incident light substantially perpendicular to the wire grids 110, amongincident light from an internal light source device (not shown), istransmitted through the wire grids 110 and transmitted through theliquid layer 300. Therefore, the display state of the electrowettingdisplay panel 400 is a bright state.

FIG. 7 is a cross-sectional view illustrating a display device includingthe electrowetting display panel of FIG. 2.

The electrowetting display panel 400 illustrated in FIG. 7 issubstantially the same as the electrowetting display panel 400illustrated in FIG. 2.

Referring to FIGS. 2 and 7, the display device 800 according to thepresent embodiment includes the electrowetting display panel 400 and abacklight unit 700.

The electrowetting display panel 400 includes a display substrate 100,an opposite substrate 200 and a liquid layer 300. The display substrate100 may include a first base substrate 101, a plurality of wire grids110, a gate insulation layer 120, an organic layer 140, a firstelectrode 150, a hydrophobic insulation layer 160 and a firsthydrophilic pixel wall 170.

The backlight unit 700 is disposed at a lower portion of theelectrowetting display panel 400. The backlight unit 700 supplies lightto the electrowetting display panel 400. The backlight unit 700 includesa light source 710, a light source receiving unit 750, a light guideplate 720, a reflection plate 730 and an optical sheet 740.

The light source 710 generates light supplied to the electrowettingdisplay panel 400. For example, light source 710 may be a cold cathodefluorescent lamp (CCFL), a flat fluorescent lamp (FFL) and alight-emitting diode (LED).

The light source receiving unit 750 holds the light source 710 andprevents light leakage through its combination with the light guideplate 720.

The light guide plate 720 is an optic plate for guiding light from thelight source 710 into a front surface of the electrowetting displaypanel 400. According to an embodiment of the present invention, thelight guide plate 720 having a wedge shape of which one end portion ofis thick and another end portion is thin is illustrated; however, theshape of the light guide plate 720 may be flat so that the thicknessesof both end portions are substantially the same.

The reflection plate 730 is disposed at a lower portion of the lightguide plate 720. The reflection plate 730 reflects light emitted througha bottom surface of the light guide plate 720 into the light guide plate720 to decrease the light leakage. The reflection plate 730 may beformed as a plate or a relatively thinner sheet of which lightreflectance is high.

The optical sheet(s) 740 is disposed between the electrowetting displaypanel 400 and the light guide plate 720. The optical sheet(s) 740 mayimprove optical characteristics. For example, the optical sheet(s) 740may include a diffusion sheet for improving the luminance uniformity oflight and a prism sheet for increasing front luminance of light.

The unit pixel area P may be used as a reflective area or a transmissivearea by embodying the wire grids 110 in the electrowetting display panel400. Therefore, an aperture ratio may be enhanced when theelectrowetting display panel 400 is driven in a reflection mode or atransmission mode.

About 50 percent of incident light is reflected and about 50 percent ofincident light is transmitted due to the characteristics of the wiregrids 110. However, reflectance and transmittance may be increased dueto the addition the reflection plate 730. For example, when theelectrowetting display panel is driven in the reflection mode, lighttransmitted through the wire grids 110, among external light that isincident light from the exterior, is reflected by the reflection plate730 and enters the wire grids 110. Therefore, optical efficiency in thereflection mode may be enhanced. Similarly, when the electrowettingdisplay panel 400 is driven in the transmission mode, reflected light bythe wire grids 110, among incident light from the light source 710, isreflected by the reflection plate 730 and enters the wire grids 110.Therefore, optical efficiency in the transmission mode may be enhanced.

When the electrowetting display panel 400 is driven in the reflectionmode, the light source 710, the light guide plate 720 and the opticalsheet 740 may be omitted. That is, the backlight unit 700 may includeonly the reflection plate 730 under display panel 400. The reflectionplate 730 may be configured as a sheet and the reflection plate 730 maybe attached to a surface opposite to a surface on which the wire grids110 are formed.

FIG. 8 is a plan view illustrating an electrowetting display panelaccording to an exemplary embodiment of the present invention. FIG. 9 isa cross-sectional view taken along a line II-II′ in FIG. 8.

The electrowetting display panel 500 of FIGS. 8 and 9 according to anexemplary embodiment of the present invention is substantially the sameas the electrowetting display panel 400 except that the electrowettingdisplay panel 500 further includes light-blocking bars 115 and secondhydrophilic pixel walls 175.

Referring to FIGS. 8 and 9, the electrowetting display panel 500includes a display substrate 100, an opposite substrate 200 and a liquidlayer 300.

The display substrate 100 includes a first base substrate 101, a gateline GL, a plurality of wire grids 110, the light-blocking bar 115, agate insulation layer 120, a data line DL, a switching element TFT, anorganic layer 140, a first electrode 150, a hydrophobic insulation layer160, a first hydrophilic pixel wall 170 and the second hydrophilic pixelwall 175.

The light-blocking bar 115 is formed on a layer on which the gate lineGL and the wire grids 110 are formed, and the light-blocking bar 115 isformed with the same material as that forming the gate line GL and thewire grids 110. The light-blocking bars 115 are formed substantiallyparallel to the gate lines GL in the unit pixel area P. Thelight-blocking bar 115 blocks light transmitted through the unit pixelarea. The light-blocking bar 115 is disposed at a position correspondingto the second hydrophilic pixel wall 175.

The first hydrophilic pixel wall 170 is disposed on the base substrate101 including the hydrophobic insulation layer 160. The firsthydrophilic pixel wall 170 defines the unit pixel area. The firsthydrophilic pixel wall 170 may be formed with a transparent material.The first hydrophilic pixel wall 170 is formed on an opaque metal line.For example, the first hydrophilic pixel wall 170 may be formed on thegate line GL and the data line DL.

The second hydrophilic pixel wall 175 divides the unit pixel area P intoa plurality of sub-pixel areas Ps1, Ps2 and Ps3. The second hydrophilicpixel wall 175 may be formed with a transparent material. The secondhydrophilic pixel wall 175 overlaps the light-blocking bar 115. A casein which two second hydrophilic pixel walls 175 divide the unit pixelarea into three sub-pixel areas Ps1, Ps2 and Ps3 is described as anexample. However, one or more than two of the second hydrophilic pixelwalls 175 may be formed in the unit pixel area P. A hole pattern 155 ofthe first electrode 150 is formed to correspond to the respectivesub-pixel areas Ps1, Ps2 and Ps3.

A method of manufacturing the display substrate 100 according to theembodiment shown in FIG. 8 is substantially the same as the method ofmanufacturing the display substrate 100 according the embodiment shownin FIG. 1, and thus repetitive descriptions may be omitted.

A gate metal layer is formed on the first base substrate 101 and thegate line GL, the gate electrode GE, the wire grids 110 and thelight-blocking bar 115 are formed by patterning the gate metal layer.The light-blocking bar 115 is formed based on the position of the secondhydrophilic pixel wall 175.

The first hydrophilic pixel wall 170 overlaps the gate line GL and thedata line DL disposed on the first base substrate 101, and the secondhydrophilic pixel wall 175 overlaps the light-blocking bar 115.

FIG. 10 is a cross-sectional view illustrating a display deviceincluding the electrowetting display panel of FIG. 9.

Referring to FIGS. 9 and 10, the display device 900 includes theelectrowetting display panel 500 and the backlight unit 700.

The electrowetting display panel 500 includes a display substrate 100,an opposite substrate 200 and a liquid layer 300. The display substrate100 may include a first base substrate 101, a gate line GL, a pluralityof wire grids 110, a light-blocking bar 115, a gate insulation layer120, a data line DL, a switching element TFT, an organic layer 140, afirst electrode 150, a hydrophobic insulation layer 160, a firsthydrophilic pixel wall 170 and a second hydrophilic pixel wall 175.

The backlight unit 700 is disposed at a lower portion of theelectrowetting display panel 500. The backlight unit 700 supplies lightto the electrowetting display panel 500. The backlight unit 700 issubstantially the same as the backlight unit of FIG. 7.

The backlight unit 700 includes a light source 710, a light sourcereceiving unit 750, a light guide plate 720, a reflection plate 730 andan optical sheet 740.

The light source 710 generates light supplied to the electrowettingdisplay panel 500.

The light source receiving unit 750 holds the light source 710 andprevents light leakage through its combination with the light guideplate 720.

The light guide plate 720 is an optic plate for guiding light from thelight source 710 into a front surface of the electrowetting displaypanel 500.

The reflection plate 730 is disposed at a lower portion of the lightguide plate 720. The reflection plate 730 reflects light emitted througha bottom surface of the light guide plate 720 into the light guide plate720 to decrease the light leakage. The reflection plate 730 may beformed as a plate or a relatively thinner sheet of which lightreflectance is high.

The optical sheet(s) 740 is disposed between the electrowetting displaypanel 500 and the light guide plate 720. The optical sheet(s) 740 mayimprove optical characteristics.

When the electrowetting display panel 500 is driven in a reflectionmode, the light source 710, the light guide plate 720 and the opticalsheet 740 may be omitted.

According to an embodiment, the unit pixel area P is divided into thesub-pixel areas Ps1, Ps2 and Ps3 by the second hydrophilic pixel walls175. Each of the hole patterns 155 is formed to correspond to therespective sub-pixel areas Ps1, Ps2 and Ps3, and thus the first liquid310 is rapidly gathered into a portion in which the hole pattern 155 ofthe first electrode 150 is formed, when a voltage is applied to theliquid layer 300. Additionally, reflectance and transmittance may beimproved by including the reflection plate 730 in the backlight unit700.

FIG. 11 is a cross-sectional view illustrating an electrowetting displaypanel according to an embodiment of the present invention.

The electrowetting display panel 600 of FIG. 11 is substantially thesame as the electrowetting display panel 400 except that theelectrowetting display panel 600 includes a half mirror 105 instead ofthe wire grids 110.

Referring to FIG. 11, the electrowetting display panel 600 includes adisplay substrate 100, an opposite substrate 200 opposite to the displaysubstrate 100 and a liquid layer 300 interposed between the displaysubstrate 100 and the opposite substrate 200.

The display substrate 100 may include a first base substrate 101, thehalf mirror 105, a passivation film 107, a gate insulation layer 120, aswitching element TFT, an organic layer 140, a first electrode 150, ahydrophobic insulation layer 160 and a first hydrophilic pixel wall 170.

The half mirror 105 reflects and transmits incident light of one surfaceof the first base substrate 101 or incident light of an opposite surfaceopposite to the one surface. The half mirror 105 may be manufactured bydepositing a thin metal layer on a glass substrate. For example, thehalf mirror 105 may be manufactured by thinly depositing aluminum,nickel, etc., on the glass substrate.

The passivation film 107 is disposed on the first base substrate 101 onwhich the half mirror 105 is disposed.

The gate insulation layer 120 is disposed on the gate electrode GE ancovers the gate electrode GE of the switching element TFT.

The electrowetting display panel 600 may include a second hydrophilicpixel wall dividing the unit pixel area P into a plurality of sub-pixelareas and a light-blocking bar blocking light transmitted through thesecond hydrophilic pixel wall.

FIGS. 12A through 12C are cross-sectional views illustrating a method ofmanufacturing the display substrate of FIG. 11.

Referring to FIG. 12A, the half mirror 105 is formed by thinlydepositing the metal layer on the first base substrate 101. Thepassivation film 107 is formed on the first base substrate 101 on whichthe half mirror 105 is formed. The passivation film 107 may be formedwith silicon nitride material or silicon oxide material, etc.

Referring to FIG. 12B, a gate metal layer (not shown) is formed on thefirst base substrate 101 on which the passivation film 107 is formed,and the gate electrode GE is formed by patterning the gate metal layer.

The gate insulation layer 120 is formed on the first base substrate 101on which the gate metal pattern is formed. A semiconductor layer 130 aand an ohmic contact layer 130 b are sequentially deposited on the firstbase substrate 101 on which the gate insulation layer 120 is formed, anda semiconductor pattern 130 is formed by patterning the semiconductorlayer 130 a and the ohmic contact layer 130 b.

A source metal layer is formed on the first base substrate 101 on whichthe semiconductor pattern 130 is formed. A source metal patternincluding a data line DL, a source electrode SE and a drain electrode DEis formed through a photoetching process of the source metal layer.

Referring to FIG. 12C, the organic layer 140 is formed on the first basesubstrate 101 on which the source metal pattern is formed, and a contacthole CNT is formed exposing an end portion of the drain electrode DE byexposing and developing the organic layer 140.

A transparent conductive layer is formed on the first base substrate 101on which the organic layer 140 including the contact hole CNT is formed.The first electrode 150 is formed by patterning the transparentconductive layer.

A case where the half mirror 105 is directly disposed on the first basesubstrate 101 is described as an example; however, the half mirror 105may be disposed on one or more layers between the first substrate 101and the liquid layer 300.

FIG. 13 is a cross-sectional view illustrating a display deviceincluding the electrowetting display panel of FIG. 11.

Referring to FIG. 13, the display device 1000 includes theelectrowetting display panel 600 and the backlight unit 700. Theelectrowetting display panel 600 includes a display substrate 100, anopposite substrate 200 and a liquid layer 300.

The display substrate 100 may include a first base substrate 101, apassivation film 107, a gate insulation layer 120, a switching elementTFT, an organic layer 140, a first electrode 150, a hydrophobicinsulation layer 160 and a first hydrophilic pixel wall 170.

The backlight unit 700 is disposed at a lower portion of theelectrowetting display panel 600. The backlight unit 700 supplies lightto the electrowetting display panel 600. The backlight unit 700 includesa light source 710, a light source receiving unit 750, a light guideplate 720, a reflection plate 730 and an optical sheet 740.

The light source 710 generates light supplied to the electrowettingdisplay panel 500.

The light source receiving unit 750 holds the light source 710 andprevents light leakage through its combination with the light guideplate 720.

The light guide plate 720 is an optic plate for guiding light from thelight source 710 into a front surface of the electrowetting displaypanel 500.

The reflection plate 730 is disposed at a lower portion of the lightguide plate 720. The reflection plate 730 reflects light emitted througha bottom surface of the light guide plate 720 into the light guide plate720 to decrease the light leakage. The reflection plate 730 may beformed as a plate or a relatively thinner sheet of which lightreflectance is high.

The optical sheet(s) 740 is disposed between the electrowetting displaypanel 600 and the light guide plate 720. The optical sheet(s) 740 mayimprove optical characteristics.

When the electrowetting display panel 500 is driven in a reflectionmode, the light source 710, the light guide plate 720 and the opticalsheet 740 may be omitted.

According to an embodiment, the unit pixel P may be used as a reflectivearea or a transmissive area by including the half mirror 105, amanufacturing process may be simplified and manufacturing costs may bedecreased. Additionally, reflectance and transmittance may be improvedby including the reflection plate 730 in the backlight unit 700.

According to the embodiments of the present invention, an aperture ratiomay be improved because the entire area of a unit pixel area may be usedas a reflective area or a transmissive area, in a reflection mode or atransmission mode. Additionally, light efficiency may be enhanced byrecycling light leaked by a reflection-transmission part, by including areflection member in a lower portion of an electrowetting display panel.

The foregoing is illustrative of embodiments of the present inventionand is not to be construed as limiting thereof. Although a few exampleembodiments of the present invention have been described, those skilledin the art will readily appreciate that many modifications are possiblein the example embodiments without materially departing from the scopeof the present invention. Accordingly, all such modifications areintended to be included within the scope of the present invention asdefined in the claims.

1. A display substrate comprising: a base substrate; areflection-polarization member disposed on the base substrate, whereinthe reflection-polarization member reflects and polarizes incidentlight; a first electrode disposed in a unit pixel area; an insulationlayer disposed on the first electrode; and a first pixel wall disposedon the insulation layer, wherein the first pixel wall defines the unitpixel area.
 2. The display substrate of claim 1, wherein thereflection-polarization member comprises a plurality of wire gridsspaced apart from each other at a uniform distance.
 3. The displaysubstrate of claim 2, further comprising a switching element connectedto a gate line, and a data line crossing the gate line, wherein thefirst pixel wall overlaps the gate line and the data line.
 4. Thedisplay substrate of claim 1, wherein the reflection-polarization membercomprises a half mirror.
 5. The display substrate of claim 1, furthercomprising at least one second pixel wall dividing the unit pixel areainto at least one sub-pixel area.
 6. The display substrate of claim 5,further comprising a light-blocking bar overlapping the second pixelwall.
 7. The display substrate of claim 5, wherein the first electrodecomprises at least one pattern.
 8. The display substrate of claim 7,wherein the pattern is formed in the sub-pixel area.
 9. A method ofmanufacturing a display substrate, the method comprising: forming aswitching element and a reflection-polarization member on a basesubstrate, wherein the reflection-polarization member reflects andpolarizes incident light; forming a first electrode on the basesubstrate including the switching element and thereflection-polarization member; forming an insulation layer on the basesubstrate including the first electrode; and forming a first pixel wallon the base substrate including the insulation layer, wherein the firstpixel wall defines a unit pixel area.
 10. The method of claim 9, whereinforming the switching element and the reflection-polarization membercomprises: forming a gate pattern having a gate electrode by patterninga gate metal layer on the base substrate, wherein the gate electrode isconnected with a gate line and a plurality of wire grids; forming a gateinsulation layer on the base substrate including the gate pattern;forming a semiconductor pattern on the base substrate including the gateinsulation layer, wherein the semiconductor pattern overlaps the gateelectrode at least in part; and forming a source pattern by patterning asource metal layer on the base substrate including the semiconductorpattern, wherein the source pattern includes a data line intersectingthe gate line, a source electrode connected to the data line and a drainelectrode spaced apart from the source electrode.
 11. The method ofclaim 10, wherein the wire grids are formed using laser interferencelithography or nanoimprint lithography.
 12. The method of claim 10,wherein the first pixel wall overlaps with gate line and the data line.13. The method of claim 10, further comprising: forming an organic layeron the base substrate including the source pattern; and forming acontact hole in the organic layer exposing the drain electrode, whereinthe first electrode is electrically connected to the drain electrodethrough the contact hole.
 14. The method of claim 9, wherein forming theswitching element and the reflection-polarization member comprises:forming a half mirror by depositing a metal layer on the base substrate;forming a passivation film on the base substrate including the halfmirror; forming a gate pattern by patterning a gate metal layer on thebase substrate including the passivation film, wherein the gate patterncomprises a gate line and a gate electrode connected to the gate line;forming a gate insulation layer on the base substrate including the gatepattern; forming a semiconductor pattern on the base substrate includingthe gate insulation layer, wherein the semiconductor pattern overlapsthe gate electrode at least in part; and forming a source pattern bypatterning a source metal layer on the base substrate including thesemiconductor pattern, wherein the source pattern includes a data lineintersecting the gate line, a source electrode connected to the dataline and a drain electrode spaced apart from the source electrode. 15.An electrowetting display panel comprising: a display substratecomprising a first base substrate, a reflection-polarization memberdisposed on the first base substrate to reflect and polarize incidentlight, a first electrode disposed on the reflection-polarization member,and a first pixel wall disposed on the first electrode, wherein thefirst pixel wall defines a unit pixel area; an opposite substratepositioned opposite to the display substrate, the opposite substratecomprising a color filter and a second electrode formed on the colorfilter; and a liquid layer interposed between the display substrate andthe opposite substrate, the liquid layer comprising a first liquidhaving a material absorbing light and a second liquid having a specificgravity different from the specific gravity of the first liquid.
 16. Theelectrowetting display panel of claim 15, wherein thereflection-polarization member comprises a plurality of wire gridsspaced apart from each other at a uniform distance.
 17. Theelectrowetting display panel of claim 15, wherein thereflection-polarization member comprises a half mirror.
 18. Theelectrowetting display panel of claim 15, further comprising at leastone second pixel wall dividing the unit pixel area into at least onesub-pixel area.
 19. The electrowetting display panel of claim 18,further comprising a light-blocking bar overlapping the second pixelwall.
 20. The electrowetting display panel of claim 15, wherein thefirst electrode comprises at least one hole pattern.